Abstract: A process for the preparation of new copolymers of olefins or olefins and non-conjugated dienes with unsaturated furan and/or thiophene derivatives, by co-ordination catalysis is disclosed.The copolymers of present invention are characterized by the fact that the monomers derived from furan or thiophene have the formulaWhere X represents oxygen or sulphur, p equals 0 or 1, and R.sub.1 represents, when p equals 0, a vinyl radical orm being an integer from 0 to 12, and, when p equals 1, an alkenyl radical of from 2 to 20 carbon atoms.These copolymers can replace polyolefins or copolymers of olefins or olefins and dienes, in cases where resistance to ultra-violet radiation is needed.